Propellant with acrylate copolymer binder and butanetriol trinitrate plasticizer

ABSTRACT

Butanetriol trinitrate (BTTN) is used as a partial or complete replacement for 1,2,3-tris(1,2-bis(difluoramino)ethoxy)propane (TVOPA) in a typical NF-smokeless propellant composition. Substituting butanetriol trinitrate for TVOPA is particularly attractive because it results in a marked reduction in cost of the propellant while providing an increase in performance of the propellant.

United States Patent 1 Sayles [4 1 Oct. 21, 1975 4] PROPELLANT WITH ACRYLATE COPOLYMER BINDER AND BUTANETRIOL TRINITRATE PLASTICIZER [75] Inventor: David C. Sayles, Huntsville, Ala.

[73] Assignee: The United States of America as represented by the Secretary of the Army, Washington, DC.

[22] Filed: July 24, 1970 [2]] Appl. No.: 64,868

[44] Published under the Trial Voluntary Protest Program on January 28, 1975 as document no. B 64,868.

[52] US. Cl. 149/19.3; l49/l9.9l; 149/38; 149/92 [51] Int. Cl. C06D 5/06 [58] Field of Search 149/19, 20, 92, 19.91, 149/38, 19.3

[56] References Cited UNITED STATES PATENTS 3,117,044 1/1964 Sauer 149/92 X Visnov et al 149/92 X Nakagawa et al. l49/l9.6

Primary Examiner-Benjamin R. Padgett Assistant ExaminerE. A. Miller Attorney, Agent, or FirmNathan Edelberg; Robert P. Gibson; Jack W. Voigt [57] ABSTRACT 9 Claims, No Drawings PROPELLANT WITH ACRYLATE COPOLYMER BINDER AND BUTANETRIOL TRINITRATE PLASTICIZER BACKGROUND OF THE INVENTION High energy smokeless type propellants containing both ammonium perchlorate (inorganic oxidizer) and cyclotetramethylenetetranitramine (HMX) and cyclotrimethylenetrinitramine (RDX) (organic oxidizers) have been utilized.

Acrylic prepolymers (e.g., ethyl acrylate-acrylic acid copolymers) have been used in high energy NF propellants containing ammonium perchlorate and aluminum, and in non-aluminized low signature propellants with HMX or RDX as the oxidizer. The technique for prepolymers preparation and characterization and for propellant preparation are well understood.

HMX and/or RDX have been utilized in heatresistant granulated propellant compositions as disclosed in US. Pat. No. 3,386,868.

HMX and/or RDX have been utilized in smokeless propellant compositions. The use of these organic oxidizers has greatly reduced the amount of smoke in the exhaust gases from the burning propellant.

Several compounds derived from exploratory development in propellant chemistry have been used in propellant formulations. One such compound, the high energy compound, TVOPA, has been investigated as a plasticizer. The high cost of TVOPA, however, has

stimulated an interest and need for a less costly compound which will still deliver a high quantity of energy when used in propellants.

An object of this invention is to provide a replacement of NF-plasticizer with a nitratoplasticizer to thereby effect a marked reduction in the cost of the propellant and simultaneously bring about a considerable increase in the performance (specific impulse) of the propellant wherein used.

Anotherobject of this invention is to provide a propellant composition wherein a deletion of ammonium perchlorate and a replacement of TVOPA can be accomplished which'results in an improvement in performance along with further improvement to the smokeless properties of the propellant.

SUMMARY OF THE INVENTION Butanetriol trinitrate (BTTN) is used as a partial or complete replacement for 1,2,3, tris[l,2- bis(difluoramino)ethoxy]propane in a propellant formulation to provide increased performance. Because of ADDITIONAL INGREDIENTS AMOUNT Acrylate-acrylic acid copolymer 4-l0 TVOPA 0-l5 HMX or RDX 40-60 AP 0-30 Diepoxydicyclohexyl carboxylate 0.5-2.0 Carbon black 0.5-l.0

BTTN can be used in amounts from about 10 to about 30 percent. The total quantities of each ingredient used in percent by weight will be 100 percent; therefore, the range for formulation of each ingredient permits many desirable compositions to be compounded while at the same time maintaining a high level of performance of the resultant propellant.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The propellant compositions of this invention employ BTTN in amounts from about 10 to about 30 percent by weight of the propellant composition. In compositions where less smoke is desired from the exhaust gases, no ammonium perchlorate is included in the formulation. Other compositions may include, in addition to BTTN, the following ingredients: AP up to about 30 percent by weight of the propellant composition; TVOPA in amounts from 0 to 15 percentby weight of the propellant composition; HMX or RDX from about 40 to about 60 percent by weight of the propellant ingredients; diepoxydicyclohexyl carboxylate (curing agent and crosslinking agent) from about 0.5 to about 2.0 percent by weight of the propellant composition; carbon black from about 0.5to about 1.0 percent by weight of the propellant composition; and acrylateacrylic acid copolymer in amounts from about 4 to about 10 percent by weight of the propellant composition.

Ethyl acrylate-acrylic acid copolymer (EA/AA) is representive of many other copolymers of the acrylateacrylic acid type (e.g., methyl, propyl, butyl acrylate, etc., -acrylic acid copolymers) which are generally constituted of from about to 96 parts acrylate and from about 4 to about 10 parts acrylic acid. The ethyl acrylate-acrylic acid set forth in Table I is constituted of about parts ethyl acrylate to about 5 parts acrylic acid. The acrylate-acrylic acid copolymers act as binder for the propellant composition. The data appearing in Table I below is derived from testing the corresponding compositions (A-D), also set forth in Table The products in the exhaust gases for compositions (A-D) are listed as percent.

TVOPA is a difluoramino plasticizer for an acrylateacrylic acid copolymer binder which when cured forms the energetic binder for the propellant system. TVOPA is prepared by reacting tris(vinoxy)propane (prepared in accordance with US. Pat. No. 2,969 ,400) with tetrafluorohydrazine. TVOPA contains two high energy difluoramino groups, NF which have undergone addition to each of the three vinoxy groups of the starting reactant, tris(vinoxy)propane. The reaction of tetrafluorohydrazine with tris(vinoxy)propane to form TVOPA is conducted under pressure in the range of 500 mm of mercury up to about 600 psig and temperature ranges of about 0 to C. The reaction is carried out in the presence of an inert volatile organic solvent, preferably one that is a suitable solvent for both the TVOPA as well as the reactant. Aromatic and aliphatic hydrocarbons, chlorinated hydrocarbons, ethers, and ketones may be employed as the solvent. Typical solvents include diethyl etherQdipropyl ether, pentane, hexane, chloroform, carbon tetrachloride, methylene chloride, benzene, toluene, xylene, and acetone.

TVOPA in large quantities would need to be manufactured from NH as the starting material in conjunction with the reaction appearing below as illustrations since neither nitrogen trifluoride nor tetrafluorohydrazine are commercially produced in large quantities.

(l) 2NH 6F 2NF 6HF catalyst N F (2) HOCH .CHOH.CH OH CL.CH:CH H Cz- TABLE 1 EFFECT OF SUBSTlTUTlON OF BTTN FOR TVOPA INGREDIENT COMPOSITION A B D 'EA/AA (95:5) 4.6 4.60 5.7 4.6 TVOPA 25.7 12.85 8.0 0.0 BTTN 0.0 12.85 23.8 25.7 HMX 48.5 48.50 60.1 48.5 AP 19.2 19.20 0.0 19.2 Diepoxydicyclohexyl carboxylate 1.5 1.50 1.8 1.5

Carbon black 0.5 0.50 0.6 0.5 TOTAL WT.% 100.0 100.00 100.0 100.0 C* 5152 5416 5220 4319 C, 1.562 1.575 1.565 1.587 lspt 250.1 265.1 253.9 262.4

HCl 3.747 3.885 4.087

The data set forth in Table 1 indicates that the substitution of half the TVOPA with BTTN results in an increase in specific impulse from 250.1 to 265.1 lbfsec/lbm. This is equivalent to a second increase a significant achievement. Substitution of all of the TVOPA with BTTN results in somewhat lesser improvement in specific impulse 262.4 lbf-sec/lbm. The deletion of ammonium perchlorate from Composition A, and replacement of 75% of TVOPA with BTTN results in a 4 lbf-sec/lbm improvement over the basic formulation.

The manufacture of BTTN does not involve major changes or construction of new production plants or facilities. Plants and facilities exist which can commerically produce BTTN. The following series of chemical reactions depict the ease of manufacture of BTTN from readily-available raw materials:

+H /catalyst HOCH .CHOH.CH .CH OH +nitration O )O NOCH .CH(ONO ).CH

CH ONO The cost of BTTN would be radially less than TVOPA. Cost basis of BTT at a starting cost of 1.0 per unit would be increased from about 2.0 to about 5.0 per unit after nitration of BTT to BTTN. The minimum cost basis for TVOPA would be about 20.0 to about 30.0 per unit which would be several times the cost of BTTN. These figures are approximations, but the relative differences in cost are based on considerations of their method of manufacture given hereinabove. However, the present state of the art indicates that the figures are realistic for use in planning purposes or cost comparison of BTTN with TVOPA. In any event, the cost estimates for BTTN manufacture indicate that a propellant with improved performance can be obtained with a considerable savings in cost corresponding to the amount of replacement of TVOPA with BTTN in the propellant formulation. Additional benefits are achieved from using BTTN since its oxidizer properties permits deleting AP from propellant formulations which are desired for use where less smokiness is essential for purpose of military concealment.

1 claim:

1. A propellant composition comprising a binder of ethyl acrylate-acrylic acid copolymer; a curing agent of diepoxydicyclphexyl carboxylate; butanetriol trinitrate; an organic oxidizer selected from cyclotetramethylenetetranitramine and cyclotrimethylenetrinitramine; 1 .2,3-tris[l ,2-tri(difluoramino)- ethoxy]propane; carbon black additive; and ammonium perchlorate oxidizer.

2. The propellant composition of claim 1 wherein said copolymer is constituted of from about to about 96 parts ethyl acrylate and from about 4 to about 10 parts acrylic acid, said copolymer being present in amounts from about 4 to about 10 percent by weight of said propellant composition; said diepoxydicyclohexyl carboxylate is present in amounts from about 0.5 to about 2.0 percent by weight of said propellant composition; said butanetriol trinitrate is present in amounts from about 10 to about 30 percent by weight of said propellant composition; said l,2,3-tris[1,2- bis(difiuoroamino)ethoxylpropane is present in amounts up to about 15 percent by weight of said propellant composition; said organic oxidizer selected from cyclotetramethylenetetranitramine and cyclotrimethylenetrinitramine is present in amounts from about 40 to about 60 percent by weight of said propellant composition; said ammonium perchlorate oxidizer is present in amounts up to about 30 percent by weight of said propellant composition; and said carbon black additive is present in amounts from about 0.5 to about 1.0 percent by weight of said propellant composition.

3. The propellant composition of claim 2 wherein said copolymer is present in an amount of about 4.6 percent by weight of said propellant composition; said diepoxydicyclohexyl carboxylate is present in an amount of about 1.5 percent by weight of said propellant composition: said butanetriol trinitrate is present in an amount of about 12.85 percent by weight of said propellant composition; said organic oxidizer selected is cyclotetramethylenetetranitramine which is present in an amount of about 48.5 percent by weight of said propellant composition; said ammonium perchlorate oxidizer is present in an amount of about 19.2 percent by weight of said propellant composition; said 1,2,3- tris[l,2-bis(difluoramino)ethoxy]propane is present in an amount of about 12.85 percent by weight of said propellant composition; and said carbon black additive is present in an amount of about 0.5 percent by weight of said propellant composition.

4. A propellant composition comprising a binder of ethyl acrylate-acrylic acid copolymer; a curing agent of diepoxydicyclohexyl carboxylate; butanetriol trinitrate; an organic oxidizer selected from cyclotetramethylenetetranitramine I and cyclotrimethylenetrinitramine; 1,2,3-tris [l,2-bis(difluoramino)- ethoxylpropane; and carbon black additive.

5. The propellant composition of claim 4 wherein said copolymer is constituted of 90 to about 96 parts ethyl acrylate and from about 4 to about 10 parts acrylic acid, said copolymer being present in amounts from about 4 to about percent by weight of said propellant composition; said diepoxydicyclohexyl carboxylate is present in amounts from about 0.5 to about 2.0 percent by weight of said propellant composition; said butanetriol trinitrate is present in amounts from about 10 to 30 percent by weight of said propellant composition; said l,2,3-tris[ 1,2-bis-(difluoramino )ethoxy]propane is present in amounts up to about percent by weight of said propellant composition; said organic oxidizer selected from cyclotetramethylenetranitramine and cyclotrimethylenetrinitramine is present in amounts from about 40 to about 60 percent by weight of said propellant composition; and said carbon black additive is present in amounts from about 0.5 to about 1.0 percent by weight of said propellant composition.

6. The propellant composition of claim 5 wherein said copolymer is present in amounts of about 5.7 percent by weight of said propellant composition; said diepoxydicyclohexyl carboxylate is present in an amount of about 1.8 percent by weight of said propellant composition; said butanetriol trinitrate is present in an amount of about 23.8 percent by weight of saidpropellant composition; said organic oxidizer selected is cyclotetramethylenetetranitramine which is present in .an amount of about 60.1 percent by weight of said propellant composition; said 1,2,3-tris[ l,2-bis(difluoramino)ethoxy]propane is present in an amount of about 8.0 percent by weight of said propellant composition; and said carbon black additive is present in an amount of about 0.6 percent by weight of said propellant composition.

7. A propellant composition comprising a binder of ethyl acrylate-acrylic acid copolymer; a curing agent of diepoxydicyclohexyl carboxylate; butanetriol trinitrate; an organic oxidizer selected from cyclotetramethylenetetranitramine and cyclotrimethylenetrinitramine; ammonium perchlorate oxidizer;

and carbon black additive.

8. The propellant composition of claim 7 wherein said copolymer is constituted of to about 96 parts ethyl acrylate and from about 4 to about 10 parts acrylic acid, said copolymer being present in amounts from about 4 to about 10 percent by weight of said propellant composition; said diepoxydicyclohexyl carboxylate is present in amounts from about 0.5 to about 2.0 percent by weight of said propellant composition; said butanetriol trinitrate is present in amounts from about 10 to about 30 percent by weight of said propellant composition; said ammonium perchlorate oxidizer is present in amounts up to about 30 percent by weight of said propellant composition; said organic oxidizer selected from cyclotetramethylenetetranitramine and cyclotrimethylenetrinitramine is present in amounts from about 40 to about 60 percent by weight of said propellant composition; and said carbon black additive is present in amounts fromabout 0.5 to about 1.0 percent by weight of said propellant composition.

9. The propellant composition of claim 4 wherein said copolymer is present in amount of about 4.6 percent by weight of said propellant composition; said diepoxydicyclohexyl carboxylate is present in an amount of about 1.5 percent by weight of said propellant composition; said butanetriol trinitrate is present in an amount of about 25.7 percent by weight of said propellant composition; said organic oxidizer selected is cyclotetramethylenetetranitramine which is present in an amount of about 48.5 percent by weight of said composition; said ammonium perchlorate oxidizer is present in amount of about 19.2 percent by weight of said propellant composition; and said carbon black additive is present in an amount of about 0.5 percent by weight of said propellant composition. 

1. A propellant composition wherein comprising a binder of ethyl acrylate-acrylic acid copolymer; a curing agent of diepoxydicyclphexyl carboxylate; butanetriol trinitrate; an organic oxidizer selected from cyclotetramethylenetetranitramine and cyclotrimethylenetrinitramine; 1,2,3-tris-propane; carbon black additive; and ammonium perchlorate oxidizer.
 2. The propellant composition of claim 1 wherein said copolymer is constituted of from about 90 to about 96 parts ethyl acrylate and from about 4 to about 10 parts acrylic acid, said copolymer being present in amounts from about 4 to about 10 percent by weight of said propellant composition; said diepoxydicyclohexyl carboxylate is present in amounts from about 0.5 to about 2.0 percent by weight of said propellant composition; said butanetriol trinitrate is present in amounts from about 10 to about 30 percent by weight of said propellant composition; said 1,2,3-tris(1,2-bis(difluoroamino)ethoxy)propane is present in amounts up to about 15 percent by weight of said propellant composition; said organic oxidizer selected from cyclotetramethylenetetranitramine and cyclotrimethylenetrinitramine is present in amounts from about 40 to about 60 percent by weight of said propellant composition; said ammonium perchlorate oxidizer is present in amounts up to about 30 percent by weight of said propellant composition; and said carbon black additive is present in amounts from about 0.5 to about 1.0 percent by weight of said propellant composition.
 3. The propellant composition of claim 2 wherein said copolymer is present in an amount of about 4.6 percent by weight of said propellant composition; said diepoxydicyclohexyl carboxylate is present in an amount of about 1.5 percent by weight of said propellant composition: said butanetriol trinitrate is present in an amount of about 12.85 percent by weight of said propellant composition; said organic oxidizer selected is cyclotetramethylenetetranitramine which is present in an amount of about 48.5 percent by weight of said propellant composition; said ammonium perchlorate oxidizer is present in an amount of about 19.2 percent by weight of said propellant composition; said 1,2,3-tris-1,2-bis(difluoramino)ethoxy)propane is present in an amount of about 12.85 percent by weight of said propellant composition; and said carbon black additive is present in an amount of about 0.5 percent by weight of said propellant composition.
 4. A PROPELLANT COMPOSITION COMPRISING A BINDER OF ETHYL ACRYLATE-ACRYLIC ACID COPOLYMER, BUTANETRIOL TRINITRATE, AND ORGA YDICYCLOHEXYL CARBOXYLATE, BUTANETRIOL TRINITRATE, AND ORGANIC NIC OXIDIZER SELECTED FROM CYCLOTERAMETHYLENETERANITRAMINE AND CYCLOTRIMETHYLENETRINITRAMINE: 1,2,3-TRIS (1,2-BIS(DIFLUORAMINO)-ETHOXY)PROPANE, AND CARBON BLACK ADDITIVE.
 5. The propellant composition of claim 4 wherein said copolymer is constituted of 90 to about 96 parts ethyl acrylate and from about 4 to about 10 parts acrylic acid, said copolymer being present in amounts from about 4 to about 10 percent by weight of said propellant composition; said diepoxydicyclohexyl carboxylate is present in amounts from about 0.5 to about 2.0 percent by weight of said propellant composition; said butanetriol trinitrate is present in amounts from about 10 to 30 percent by weight of said propellant composition; said 1,2,3-tris1,2-bis-(difluoramino)ethoxy)propane is present in amounts up to about 15 percent by weight of said organic propellant composition; said oxidizer selected from cyclotetramethylenetranitramine and cyclotrimethylenetrinitramine is present in amounts from about 40 to about 60 percent by weight of said propellant composition; and said carbon black additive is present in amounts from about 0.5 to about 1.0 percent by weight of said propellant composition.
 6. The propellant composition of claim 5 wherein said copolymer is present in amounts of about 5.7 percent by weight of said propellant composition; said diepoxydicyclohexyl carboxylate is present in an amount of about 1.8 percent by weight of said propellant composition; said butanetriol trinitrate is present in an amount of about 23.8 percent by weight of said propellant composition; said organic oxidizer selected is cyclotetramethylenetetranitramine which is present in an amount of about 60.1 percent by weight of said propellant composition; said 1,2,3-tris(1,2-bis(difluoramino)ethoxy)is present in an amount of about 8.0 percent by weight of said propellant composition; and said carbon black additive is present in an amount of about 0.6 percent by weight of said propellant composition.
 7. A propellant composition comprising a binder of ethyl acrylate-acrylic acid copolymer; a curing agent of diepoxydicyclohexyl carboxylate; butanetriol trinitrate; an organic oxidizer selected from cyclotetramethylenetetranitramine and cyclotrimethylenetrinitramine; ammonium perchlorate oxidizer; and carbon black additive.
 8. The propellant composition of claim 7 wherein said copolymer is constituted of 90 to about 96 parts ethyl acrylate and from about 4 to about 10 parts acrylic acid, said copolymer being present in amounts from about 4 to about 10 percent by weight of said propellant composition; said diepoxydicyclohexyl carboxylate is present in amounts from about 0.5 to about 2.0 percent by weight of said propellant composition; said butanetriol trinitrate is present in amounts from about 10 to about 30 percent by weight of said propellant composition; said ammonium perchlorate oxidizer is present in amounts up to about 30 percent by weight of said organic propellant composition; said oxidizer selected from -cyclotetramethylenetetranitramine and cyclotrimethylenetrinitramine is present in amounts from about 40 to about 60 percent by weight of said propellant composition; and said carbon black additive is present in amounts from about 0.5 to about 1.0 percent by weight of said propellant composition.
 9. The propellant composition of claim 4 wherein said copolymer is present in amount of about 4.6 percent by weight of said propellant composition; said diepoxydicyclohexyl carboxylate is present in an amount of about 1.5 percent by weight of said propellant composition; said butanetriol trinitrate is present in an amount of about 25.7 percent by weight of said propellant composition; said organic oxidizer selected is cyclotetramethylenetetranitramine which is present in an amount of about 48.5 percent by weight of said composition; said ammonium perchlorate oxidizer is present in amount of about 19.2 percent by weight of said propellant composition; and said carbon black additive is present in an amount of about 0.5 percent by weight of said propellant composition. 